基于DGT技术的黄河上游典型水库沉积物氮磷释放与污染源解析

Sediment Release and Pollution Source Analysis of Typical Reservoirs in the Upper Reaches of the Yellow River Based on DGT Technology

针对黄河上游河库连通背景下水库的污染源解析不足的问题,基于薄膜梯度扩散和高分辨率孔隙水采样,分析了黄河上游典型水库——沈家河水库的污染特征和扩散通量.结果表明,清水河入库口水质为劣Ⅴ类,沉积物为重度污染状态.各点位上覆水可溶性磷酸盐(SRP)平均值低于孔隙水,表明沉积物SRP因浓度梯度向上扩散.各点位DGT-P与DGT-Fe的相关性及沉积物-水界面浓度差存在空间异质性,1号的沉积物DGT-P释放受Fe-P还原释放主导,2号的表层沉积物DGT-P释放能力较差,3号的表层沉积物DGT-P的释放能力较强,可根据释放机制采取不同治理措施.沉积物-水界面附近1号(4~8 mm)、2号(8~20 mm)和3号(-8~8 mm)发生NH_(4)^(+)-N浓度减小和NO_(3)^(-)-N浓度增加的现象.沉积物释放导致的TP、TN和NH_(4)^(+)-N负荷增加量分别占总量的100%、78.3%和56.5%,表明沉积物释放是负荷的主要来源,但是清水河输入对氮的影响不可忽略.结果为黄河上游水库污染源解析和治理提供了参考.

In order to solve the problem of insufficient analysis of the pollution sources of the reservoir under the river-reservoir connectivity of the upper reaches of the Yellow River,this study analyzed the pollution characteristics and diffusion flux of a typical reservoir in the upper reaches of the Yellow River(Shenjiahe Reservoir)based on the DGT and HR-Peeper technology.The results showed that the water quality at the entrance of the reservoir was inferior to Class V,and the reservoir sediments were under heavy pollution.The average concentration of soluble phosphate(SRP)in the overlying water at each point was lower than that of the pore water,indicating that the SRP of sediment diffused upward due to the concentration gradients.The correlations between DGT-P and DGT-Fe and the concentration difference at the sediment-water interface were spatially heterogeneous.The sediment DGT-P release was dominated by Fe-P reduction release at point 1,the ability of surface sediment DGT-P release was poor at point 2,and surface sediment DGT-P had strong release ability;thus,different governance measures could be taken according to the release mechanisms.The concentrations of NH_(4)^(+)-N decreased and the concentrations of NO_(3)^(-)-N increased at point 1(4-8 mm),point 2(8-20 mm),and point 3(-8-8 mm)near sediment-water interface.The increase in TP,TN,and NH_(4)^(+)-N loading mainly came from the sediments release,and the impact of external input from the Qingshui River on nitrogen cannot be ignored.These results provide a reference for the analysis of pollution sources and the management of river reservoirs in the upper reaches of the Yellow River.